Effect of oxyethylene numbers on the pharmacokinetics of menatetrenone incorporated in oil-in-water lipid emulsions prepared with polyoxyethylene-polyoxypropylene block copolymers and soybean oil in rats.
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We have prepared lipid emulsions of approximately 200 nm in diameter with soybean oil (SO) and a series of Pluronics with various numbers of oxyethylene units and about 60 oxypropylene units (SO/Pluronics), and studied the pharmacokinetics of menatetrenone incorporated into SO/Pluronics in rats. Emulsions of approximately 200 nm in diameter were obtained when SO contents were 2.5% and 20% (w/w) for 2.4% (w/w) PL101 and Pluronics that more than 30% was made up by oxyethylene units, respectively. The half-life of menatetrenone in plasma when oxyethylene units made up less than 30% of the Pluronic (SO/PL101 and SO/PP103) was similar to that for SO/egg yolk phosphatides (SO/EYP), but longer than that when oxyethylene units composed more than 40% of the Pluronic (SO/PP104 and SO/PF108, by 3- and 10-fold, respectively). Pretreatment with dextran sulfate 500000, an inhibitor of emulsion uptake by the reticuloendothelial system (RES), resulted in a higher plasma concentration and a lower liver uptake of menatetrenone as SO/PL101 at 10 min and SO/PP103 at 60 min, indicating that both SO/PL101 and SO/PP103 were taken up by the RES, although SO/PP103 required some time to be recognized by the RES. These findings suggested that larger numbers of oxyethylene units of Pluronics with 60 oxypropylene units were required for the longer plasma circulation of SO/Pluronics due to evasion of the RES. (+info)
Stabilization of urinary THC solutions with a simple non-ionic surfactant.
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To stabilize urinary solutions against adsorptive loss of metabolites of Delta9-tetrahydrocannabinol (THC), a non-ionic surfactant, Tergitol, was investigated to reduce the need for special handling and storage of such solutions. Addition of surfactant up to 20 times the critical micelle concentration (CMC) did not adversely affect the analytical process. Yet, at only two times CMC, surfactant was found to mitigate adsorptive loss of THC analytes under a variety of storage and handling conditions including exposure to glass and plastic surfaces, after storage in a refrigerator or freezer, and at reduced pH, where adsorptive losses were expected to be significant. On average, micellar solubilization of analyte increased the assayed concentration by 10% with a range of 3 to 20%, depending on condition, relative to solutions without surfactant. Solutions with surfactant did not fail (i.e., deviate in concentration by +/-20%) over a 49-week period, whereas those without surfactant failed by 21 weeks. These results indicate that addition of small amounts of non-ionic surfactant to solutions of urinary THC metabolites is a simple method to improve both the accuracy and precision of analyte concentrations, as determined by gas chromatography-mass spectrometry, in such solutions by mitigating adsorptive losses during storage and handling events. (+info)
The utilization of pathogen-like cellular trafficking by single chain block copolymer.
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